Q: Is JUnit just for Unit Testing or can we use it for other testing as well?

JUnit is used for unit testing. And it is used for other types of testing as well.

I don’t think of JUnit as a Unit Testing Tool. Instead, I view it as a way of running code marked as ‘runnable by JUnit’. That code is marked by @Test annotations and is often called a Test, and those ‘Tests’ are often used for Unit testing, but they don’t have to be.

JUnit can be used as a test runner for any kind of test: e.g. system and integration tests; tests which are interacting with a deployed application.